tech task: add setup script for splash site

Value

as a new dev, i want to easily be able to install and run the splash site so i can edit it without futzing with docker or yarn

Behavior

GIVEN a freshly downloaded repo

WHEN a dev runs make splash.setup
THEN the system will build the splash site docker image and install its node dependency inside the container
NOW WHEN a dev runs make splash.dev the splash site will "just work"

Edited Dec 09, 2019 by aguestuser

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